Characterization and progressive damage analysis of quasi-three-dimensional composites

The applications of fiber-reinforced polymer composites are gaining accelerated growth in aerospace, automotive, and emerging energy industries. This dissertation discusses issues concerning the characterization and progressive damage analysis of an innovative quasi-three-dimensional (Q3D) composite using finite element methods. Firstly, the average field homogenization method based on finite element analysis of representative unit cells is implemented in ABAQUS/Standard to compute the effective stiffness of the Q3D woven composite and compare with the conventional laminated and woven counterparts. Particular attention is given to the optimal choice of geometric parameters for achieving high in-plane stiffness in the Q3D woven designs. Secondly, double cantilever beam (DCB) and end-notch flexure (ENF) tests are simulated using the cohesive zone model to investigate the progressive inter-laminar delamination growth through the undulation regions in woven composites. The effects of undulation on delamination propagation in woven designs are highlighted. Next, a three-dimensional continuum damage mechanics model for the prediction of the initiation and evolution of intra-laminar damage mechanisms is developed. Combining this damage mechanics model with the cohesive zone model, different damage modes such as delamination patterns and fiber-bridging in laminated composites subjected to transverse static and low-velocity impact loadings are simulated and compared with experimental results. The necessity of in-ply matrix cracking is emphasized for the accurate prediction of delamination in laminated plates subjected to transverse static loading. Finally, using the developed three-dimensional continuum damage mechanics model and the shell-solid modeling technique, laminated, two-dimensional woven and Q3D woven composites subjected to transverse low-velocity impact are simulated in ABAQUS/Explicit. The Q3D woven composite is shown to have higher impact damage resistance than its laminated and two-dimensional woven counterparts.